Vacuum-type electric circuit interrupter

ABSTRACT

A vacuum interrupter comprises an evacuated housing into which a pair of rodlike stationary axially aligned spaced apart electrodes extend. The inner end of each electrode is capped with a cup-shaped arc runner having spiral slots therein. A cylindrical arc shield having spiral slots therein surrounds the arc runners on each electrode and the gap therebetween. A pair of simultaneously movable bridging contacts are located in the housing on opposite sides thereof. Each bridging contact is reciprocably movable transversely to the axis on which the electrodes lie. Each bridging contact has an &#39;&#39;&#39;&#39;open&#39;&#39;&#39;&#39; position wherein it lies in or outside of an aperture in the cylindrical arc shield. Each bridging contact is movable from &#39;&#39;&#39;&#39;open&#39;&#39;&#39;&#39; to a &#39;&#39;&#39;&#39;closed&#39;&#39;&#39;&#39; position (and vice versa), through the aperture in the cylindrical arc shield and through apertures in the arc runners, wherein the bridging contact engages both electrodes. Each electrode is cylindrically shaped and that portion of the bridging contact engageable with the electrode is provided with a V-shaped notch which is partially filled with high vapor pressure metal such as bismuth.

United States Patent [72] lnventor Donald E. Weston Chicago, Ill. [21] Appl. No. 856,724 [22] Filed Sept. 10, 1969 [45] Patented Apr. 20, 1971 [73 1 Assignee Allis-Chalmers Manufacturing Company Milwaukee, Wis.

[54] VACUUM TYPE ELECTRIC CIRCUIT Primary Examiner-Robert S. Macon Attorneys-Thomas F. Kirby, Lee H. Kaiser and Robert B.

Benson ABSTRACT: A vacuum interrupter comprises an evacuated housing into which a pair of rodlike stationary axially aligned spaced apart electrodes extend. The inner end of each electrode is capped with a cup-shaped arc runner having spiral slots therein. A cylindrical arc shield having spiral slots therein surrounds the arc runners on each electrode and the gap therebetween. A pair of simultaneously movable bridging contacts are located in the housing on opposite sides thereof. Each bridging contact is reciprocably movable transversely to the axis on which the electrodes lie. Each bridging contact has an open position wherein it lies in or outside of an aperture in the cylindrical arc shield. Each bridging contact is movable from open to a closed position (and vice versa), through the aperture in the cylindrical arc shield and through apertures in the arc runners, wherein the bridging contact engages both electrodes. Each electrode is cylindrically shaped and that portion of the bridging contact engageable with the electrode is provided with a V-shaped notch which is partially filled with high vapor pressure metal such as bismuth.

PATENTEU APR20 l97l W wa VACUUM TYPE ELECTRIC CIRCUIT INTERRUPTER SUMMARY OF THE INVENTION This invention generally to electric circuit interrupters and, particularly, to vacuum-type interrupters employing movable bridging contacts and are runners.

Many types of vacuum-type electric circuit interrupters and switches are known and commercially available. Those using relatively movable butt-type contacts are limited in their power handling capability by the large mechanical force required to provide contact pressures necessary to overcome magnetic blowoff forces tending to force the contacts open. For example, a contact force of about 400 lbs/in is needed in a vacuum interrupter rated up to about 25KA. In these and other vacuum interrupters ratings are also limited by the thermal energy dissipation characteristics of the interrupters.

It is desirable, therefore, to provide improved vacuum interrupters capable of handling power levels well in excess of 25KA (for example, on the order of about 40 to 60KA) and comparable to other types of circuit interrupters, such as fluid (oil or gas) type interrupters.

In accordance with the present invention the foregoing and other objectives are met by providing an improved vacuumtype circuit interrupter which uses one or more improved bridging contacts to take advantage of magnetic blow-on" forces and which uses improved arc runners and are shields to more effectively distribute and dissipate thermal energy in the interrupters.

OBJECTS OF THE INVENTION It is an object of the present invention to provide improved circuit breakers, particularly, improved vacuum-type electric circuit interrupters and switches.

Another object is to provide improved vacuum interrupters which have increased power handling capabilities.

Another object is to provide improved vacuum interrupters having improved contact means and improved arc runner means.

Another object is to provide improved vacuum interrupters of the aforesaid character which have improved contact blow-on characteristics and improved thermal distribution and dissipation characteristics.

Another object is to provide vacuum interrupters of the aforesaid character which inherently distinguish between high current arcing and low current arcing and most effectively extinguish each type of arcing.

Another object is to provide vacuum interrupters having improved contacts which prevent dangerous current chopping and have superior antiwelding characteristics.

Another object is to provide improved vacuum interrupters of the aforesaid character which are compact, efficient, capable of being mass produced, economical, and which employ known and readily available technologies and materials in their production.

Other objects and advantages of the invention will hereinafter appear.

DESCRIPTION OF THE DRAWING The accompanying drawing illustrates a preferred embodiment of the invention but it is to be understood that the embodiment illustrated is susceptible of modification with respect to details thereof without departing from the scope of the appended claims.

In the drawing:

FIG. I is a cross-sectional view of a vacuum interrupter embodying the present invention;

FIG. 2 is a cross-sectional view taken along line [1-11 of FIG. I; and

FIG. 3 is a detailed view of one of the arc runners shown in FIG. 1.

DETAILED DESCRIPTION OF THE INVENTION Referring to FIGS. 1 and 2 of the drawing, the numeral 10 designates a vacuum-type electric circuit interrupter in accordance with the present invention which, for example, is adapted to be rated in excess of 25KA. Interrupter 10 comprises a housing 12 in which a vacuum on the order of 10 millimeters of mercury or greater is maintained. Housing 12 comprises an envelope 14 made of insulating material, such as glass or ceramic, and is provided at its opposite ends with openings which are sealed'off by end caps 16 and 18. End caps 16 and 18 each comprise a cylindrical metal collar 20 which is hermetically sealed to envelope 14 and further comprises an end plate 22 which is hermetically sealed to the metal collar.

The end plates 22 of the end caps 16 and 18, respectively, support electrically conductive stationary electrodes 24 and 26, preferrably cylindrical, which are axially aligned with each other and have their inner ends spaced apart a predetermined distance. The outer ends of the electrodes 24 and 26 are understood to be adapted to be connected in an electric circuit (not shown) which is to be controlled. Arc shields 25 and 27 in the form of metallic discs are provided on the electrodes 24 and 26, respectively. The inner end of electrode 26 is provided with an electrically conductive cup-shaped arc runner 28 which is electrically and mechanically connected thereto and which, as FIG. 3 shows, is provided with one or more spiral slots 30 extending axially therealong for are rotation purposes, as hereinafter explained. Arc runner 28 is provided on opposite sides thereof with apertures 32 for accommodating the passage of bridging contacts 34 and 36 hereinafter described. The inner end of electrode 24 is provided with an arc runner 38 which is similar in form and function to are runner 28 hereinbefore described.

The are runners 28 and 38 and the space therebetween are surrounded by an electrically conductive cylindrical arc shield and arc runner 40 which is provided with apertures 42 on opposite sides thereof for accommodating the passage of bridging contacts 34 and 36 and with one or more spiral slots 44 which extend therealong for are rotation purposes.

Arc shield 40 is mechanically supported by two tubular supporting members 46 and 48 which extend through suitable openings in the sides of envelope 14 and which also serve as the supports for the bridging contacts 34 and 36, respectively. Tubular support 46 is understood to be hermetically sealed to envelope 14 and is provided at its outer end with a closure plate 50 which is hermetically sealed in place and which has a hole 52 for accommodating a reciprocably movable control rod 54 to which bridging contact 34 is attached. A cylindrical bellows 56 is sealed between closure plate 50 and control rod 54 to permit axial movement of rod 54 while maintaining the vacuum tight integrity within housing 12. Supporting member 48 is to be understood to be similar in form and function to supporting member 46 and is provided with a closure plate 58, control rod 60 and bellows 62 similar to elements 50, 54 and 56, respectively, hereinbefore described.

Bridging contact 34, hereinbefore referred to, comprises an electrically conductive midportion 64 having spaced apart portions 66 and 68 for cooperation with the electrodes 24 and 26, respectively. As FIG. 2 shows, contact portion 66 is provided with a V-shaped slot 70 having sides 72 and 74 and an apex 76. Contact portion 66 is fabricated of low vapor 2. An interrupter according to claim 1 including an electrically conductive shield surrounding the runners on said electrodes and having an aperture therein for accommodating said bridging contact.

3. An interrupter according to claim 2 comprising a pair of bridging contacts disposed on different sides of said electrodes and wherein said shield and said are runners have apertures of accommodating both of said bridging contacts.

4. An interrupter according to claim 3 wherein said are runners are cup-shaped.

5. An interrupter according to claim 4 wherein said are runners are slotted.

6. An interrupter according to claim 5 wherein said shield is cylindrical and slotted.

7. An interrupter according to claim 6 wherein said electrodes, are runners, shield and bridging contacts are housed in a vacuumized envelope.

8. An interrupter according to claim 7 wherein said electrodes are cylindrical and wherein said bridging contacts have V-shaped slots therein for engagement with said electrodes.

9. An interrupter according to claim 8 wherein said electrodes are copper and wherein said V-shaped slots are formed in copper material and partially filled with low vapor pressure material.

10. In a vacuum-type electric circuit interrupter, an evacuated housing,

a pair of axially aligned cylindrical electrodes having spaced apart ends located in said housing,

a pair of electrically conductive arc runners connected to the ends of said electrodes,

each arc runner being cylindrical and having at least one spiral slot therein, each arc runner being further provided with a pair of apertures therein, one on either side thereof,

an electrically conductive cylindrical shield in said housing and surrounding said pair of arc runners and the space between the ends of the electrodes,

said shield having at least ones one slot therein and being further provided with a pair of apertures therein, one on either side thereof,

and a pair of bridging contacts in said housing for engagement with said electrodes and disposed on opposite sides of said electrodes,

said bridging contacts being reciprocably movable transversely to the axis on which said electrodes lie and adapted to move through the apertures in said shield and the apertures in said are runners.

11. An interrupter according to claim 10 including vapor shields disposed near the ends of said arc shield.

12. An interrupter according to claim 11 wherein said electrodes are copper, wherein said bridging contacts are copper and have V-shaped slots are partially filled with low vapor pressure material. 

1. In an electric circuit interrupter, a pair of electrodes having spaced apart ends, a electrically conductive runner surrounding the end of each electrode, each runner having at least one aperture therein, and a movable bridging contact engageable with said pair of electrodes through the apertures therein.
 2. An interrupter according to claim 1 including an electrically conductive shield surrounding the runners on said electrodes and having an aperture therein for accommodating said bridging contact.
 3. An interrupter according to claim 2 comprising a pair of bridging contacts disposed on different sides of said electrodes and wherein said shield and said arc runners have apertures of accommodating both of said bridging contacts.
 4. An interrupter according to claim 3 wherein said arc runners are cup-shaped.
 5. An interrupter according to claim 4 wherein said arc runners are slotted.
 6. An interrupter according to claim 5 wherein said shield is cylindrical and slotted.
 7. An interrupter according to claim 6 wherein said electrodes, arc runners, shield and bridging contacts are housed in a vacuumized envelope.
 8. An interrupter according to claim 7 wherein said electrodes are cylindrical and wherein said bridging contacts have V-shaped slots therein for engagement with said electrodes.
 9. An interrupter according to claim 8 wherein said electrodes are copper and wherein said V-shaped slots are formed in copper material and partially filled with low vapor pressure material.
 10. In a vacuum-type electric circuit interrupter, an evacuated housing, a pair of axially aligned cylindrical electrodes having spaced apart ends located in said housing, a pair of electrically conductive arc runners connected to the ends of said electrodes, each arc runner being cylindrical and having at least one spiral slot therein, each arc runner being further provided with a pair of apertures therein, one on either side thereof, an electrically conductive cylindrical shield in said housing and surrounding said pair of arc runners and the space between the ends of the electrodes, said shield having at least ones one slot therein and being further provided with a pair of apertures therein, one on either side thereof, and a pair of bridging contacts in said housing for engagement with said electrodes and disposed on opposite sides of said electrodes, said bridging contacts being reciprocably movable transversely to the axis on which said electrodes lie and adapted to move through the apertures in said shield and the apertures in said arc runners.
 11. An interrupter according to claim 10 including vapor shields disposed near the ends of said arc shield.
 12. An interrupter according to claim 11 wherein said electrodes are copper, wherein said bridging contacts are copper and have V-shaped slots are partially filled with low vapOr pressure material. 